1. Technical Field
The present invention relates to a heat flow meter and an electronic device.
2. Related Art
A human body temperature is maintained by heat emitted from a human body. Metabolism for maintaining this body temperature is called basal metabolism. Accordingly, when the heat emitted from a human body is measured, a metabolic rate can be known. As paths of heat emitted from a human body, there are convective heat transfer in which heat is transferred to an external environment by convection of air, water, or the like and radiative heat transfer in which heat is transferred to the surface of a surrounding object by radiation of electromagnetic waves. When a heat flow by heat transfer such as the convective heat transfer or the radiative heat transfer is measured, heat (a heat discharge) emitted from a human body can be measured.
For example, JP-A-2011-120917 discloses a technology for mounting an armband-shaped electronic device (sensor device) including a heat flow sensor (heat flux sensor) to come into contact with a skin of a wearer and measuring a heat flow from a temperature difference occurring inside the heat flow sensor by the heat transfer.
Incidentally, to accurately measure a heat flow emitted from a human body, it is necessary to transfer heat of a skin surface to the heat flow sensor without loss. The electronic device disclosed in JP-A-2011-120917 has a structure in which an attachment having flexibility and formed of metal or the like having good thermal conductivity is brought into contact with a skin surface so that heat of the skin surface is transferred to the heat flow sensor via the attachment since the heat flow sensor has no flexibility. In such a structure, however, part of the heat from the skin surface may flow out to another member before the heat is transferred to the heat flow sensor, and thus an error may occur in measurement of the heat flow.
When the heat flow sensor with no flexibility is brought into direct contact with an object having a curved surface such as a human body to suppress the transfer loss caused due to outflow of the heat, an air layer easily occurs between the heat flow sensor and the skin surface. When the air layer occurs between the heat flow sensor and the skin surface, an actual contact area between the heat flow sensor and the skin surface decreases, and thus the heat transferred to the heat flow sensor decrease. Therefore, the measured heat flow is less than the actual heat flow. As a result, a problem arises in that an error of measurement of the heat flow occurs in the heat flow sensor with no flexibility, and thus measurement accuracy of a heat discharge frost a human body deteriorates.